man/network: extend document about the default value of IPv6AcceptRA=

Prompted by #39304.

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 370ff3f969fc3deaf481494692a838553fafd64c..3e55d040b2fe028479691624321dddc70cf1ce86 100644 (file)
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -215,7 +215,8 @@
         <term><varname>Multicast=</varname></term>
         <listitem>
           <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults
-          to unset.</para>
+          to unset and the flag is unchanged. When disabled, <varname>IPv6AcceptRA=</varname> and
+          <varname>IPv6SendRA=</varname> cannot be enabled.</para>
 
           <xi:include href="version-info.xml" xpointer="v239"/>
         </listitem>
@@ -942,10 +943,19 @@ DuplicateAddressDetection=none</programlisting></para>
           <para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the interface.
           If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may trigger the
           start of the DHCPv6 client if the relevant flags are set in the RA data, or if no routers are found
-          on the link. Defaults to false for bridge devices, when <varname>IPv6Forwarding=</varname>,
-          <varname>IPv6SendRA=</varname>, or <varname>KeepMaster=</varname> is enabled. Otherwise, enabled by
-          default. Cannot be enabled on devices aggregated in a bond device or when link-local addressing is
-          disabled.</para>
+          on the link.</para>
+
+          <para>This cannot be enabled on devices aggregated in a bond device, or when IPv6 link-local
+          addressing (see <varname>LinkLocalAddressing=</varname>) or multicasting (see
+          <varname>Multicast=</varname>) is disabled. Note, multicasting is disabled by default for some
+          configurations, e.g. bridge ports. Hence, in that case <varname>Multicast=</varname> needs to be
+          explicitly enabled to make this feature usable. When <varname>IPv6SendRA=</varname>,
+          <varname>IPv6Forwarding=</varname>, or <varname>IPMasquerade=</varname> is enabled, this feature is
+          disabled by default, but can be overridden by explicitly enabling this setting. Note,
+          <varname>IPv6Forwarding=</varname> may be indirectly enabled when the global setting with the same
+          name is enabled, or when <varname>IPMasquerade=</varname> is enabled on <emphasis>any other
+          interfaces</emphasis>. See also <varname>IPv6Forwarding=</varname> and
+          <varname>IPMasquerade=</varname> for more details. Enabled by default otherwise.</para>
 
           <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA]
           section, see below.</para>